I have been know to be a little extreme... Lets get that out of the way now, lol.What would you guys say the limit is for a decent built 8.8 is then? Right now I am making anywhere from 400hp to 450hp. I have the factory traclok that acts like an open diff with 3.55's (really like this ratio). I was thinking if I kept my 8.8 (before I was considering the 9") I would put a Ford 31 spline traclok, matching axles, and a braced diff cover on it. I am not sure if I should do C clip eliminators or not since it is mostly a street car. I want to keep my rear drums for simplicity sake for now (car stops great and I don't want to deal with changing the MC). Future plans may involve a Coyote swap with a roots blower on it, a Dart 427, or heck maybe even an LSX swap someday (probably not). All of these would likely be in the 600hp+ range and I would hate to have to redo something that I could have done once the first time.
In years past, a buddy of mine had an Outlaw Radial car (this was around 2007 ish) That car made well over 2,000 HP and saw times at the track in the 7.0@200+ range, all with an 8.8 Ford rear... Point being, your wallet is the limit of the 8.8 not HP.
For a street build that will not see the track often, daily driver: Ford Racing Gears, 31 spline differential, Moser Axles, C Clip Eliminators, Welded Axle Tubes, Girdle Cover, Spherical Bushings and rock and roll (I Like this setup up to 500rwhp ish)
For a more track oriented build, other than daily driver: Ford Racing Gears, 35 Spline Spool, 35 Spline Moser Axles, 9" Housing ends, Welded Axle Tubes, Spherical Bushings, Mark Williams Main Caps (these are way nicer than any girdle cover on the market), Solid pinion sleeve (no crush collar), 1350 Drive Shaft Yoke